public class AdvertisementBoard {
    Advertisement adver;
    public void setAdvertisement(Advertisement a){
        adver = a;
    }
    public void show(){
        if(adver == null){
            System.out.println("这是一个空的广告牌");
        }else{
            adver.showAdvertisement();
            System.out.println(adver.getCorpName());
        }
    }
}
